The present invention relates to a push button overload protection switch of the type disclosed in U.S. Pat. No. 2,952,757. Such a switch includes a contact bridge configured as an approximately rectangular angle lever which is latched by an undeflected bimetal member and is thus held in its ON position. The contact bridge is mounted on a switch rod so as to be freely pivotal and displaceable in the axial direction of the switch rod. The switch rod is rigidly connected with a push button that is spring tensioned in a direction opposite to the direction of push button pressure, with the switch rod extending in the direction of push button pressure. A switch spring is provided which, during turn-off of the switch, is effective in the longitudinal direction of the switch rod opposite to the direction of push button pressure for pushing a first arm of the contact bridge against an oblique abutment of a switch housing so that the contact bridge is brought into an oblique engagement position, pivoted with respect to its ON position. In the oblique engagement position, the contact bridge engages a projection on the switch rod wherein by actuation of the push button in the direction of push button pressure, the switch spring is caused to exert pressure on the first arm of the contact bridge to pivot the contact bridge from the oblique engagement position into the ON position whereby the first arm of the contact bridge engages behind a contact piece of the bimetal member which is in its undeflected position, wherein a second arm of the contact bridge is brought into a position substantially parallel to the switch rod for pressing against a contact terminal that is fixed to the housing. Additionally, a manually actuatable device is provided for deflecting the bimetal member to thus release a turn-off movement controlled by the switch spring.
The prior art overload protection switch of the above-mentioned type is distinguished by its very small size so that a multitude of such switches can be placed in a row in a space saving manner. The manually actuatable device to deflect the bimetal is constituted by a second push button which is mounted in the switch housing so as to be displaceable parallel to the push button which switches the device on and is thereby charged by a spring which pushes it back into its inactive position. This arrangement of a second push button for manual turn-off is expensive to manufacture and takes up much space.